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BURIED OYSTER SHELL RESOURCE EVALUATION
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EASTERN REGION OF THE ALBEMARLE SOUND
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BURIED OYSTER SHELL RESOURCE
EVALUATION OF THE EASTERN REGION
OF THE ALBEMARLE SOUND
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NORTH CAROLINA
DEPARTMENT OF NATURAL AND ECONOMIC RESOURCES
DIVISION OF EARTH RESOURCES
GEOLOGY AND MINERAL RESOURCES SECTION
RALEIGH
1976
BULLETIN 85
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BURIED OYSTER SHELL RESOURCE EVALUATION
OF THE
EASTERN REGION OF THE ALBEMARLE SOUND
NORTH CAROLINA
DEPARTMENT OF NATURAL AND ECONOMIC RESOURCES
DIVISION OF EARTH RESOURCES
GEOLOGY AND MINERAL RESOURCES SECTION
RALEIGH
1976
COVER PHOTOGRAPH SHOWS ALPINE "VIBRA CORE" BEING LOWERED
INTO THE ALBEMARLE SOUND BY MEANS OF A BARGE-MOUNTED CRANE,
Edited by: Edward R. Burt
Layout by: Benjamin J. McKenzie
Printed by: State Government Printing Office
Additional copies of this publication are available from:
Department of Natural and Economic Resources
Earth Resources Division
Geology and Mineral Resources Section
P. 0. Box 27687
Raleigh, North Carolina 27611
BURIED OYSTER SHELL RESOURCE EVALUATION
OF THE
EASTERN REGION OF THE ALBEMARLE SOUND
BY
JAMES L. SAMPAIR
IN COOPERATION WITH THE
DIVISION OF MARINE FISHERIES
M - *
... A
0»* «
GEOLOGY AND MINERAL RESOURCES SECTION
This section shall, by law ". . .make such examination, survey, and mapping of the geology, mineralogy,
and topography of the state, including their industrial and economic utilization, as it may consider
necessary.
In carrying out its duties under this law, the section promotes the wise conservation and use of mineral
resources by industry, commerce, agriculture, and other governmental agencies for the general welfare of
the citizens of North Carolina.
The Section conducts a number of basic and applied research projects in environmental resource plan-ning,
mineral resource exploration, mineral statistics, and systematic geologic mapping. Services constitute
a major portion of the Section's activities and include identifying rock and mineral samples submitted by
the citizens of the state and providing consulting services and specially prepared reports to other agencies
that require geological information.
The Geology and Mineral Resources Section publishes results of its research in its own series of Bulletins,
Economic Papers, Information Circulars, Educational Series, Geologic Maps, and Special Publications. For
a complete list of publications or more information about the Section please write: Geology and Mineral
Resources Section, P. O. Box 27687, Raleigh, North Carolina 2761 1.
CONTENTS
Page
Abstract 1
Purpose and scope 1
Organization and acknowledgements 2
Fieldwork 3
Subbottom profiling 3
Core sampling 5
Office and laboratory work , 6
Interpretation and results 7
Area A 8
Prospect 1 - Haul over Point 8
Prospect 2 - Peter Mashoes Creek 8
Prospect 3 - Collington Shoals 8
Prospect 4 - Mashoes Light 8
Prospect 5 9
Area B 9
Prospect 6 - Croatan Channel 9
Area C 9
Prospect 7 - Croatan Sound marker "21" 9
Prospect 8 - position mark 23 10
Prospect 9 - Cedar Bush Bay 10
Dredging and the environment 10
Physical effects 12
Biological effects 12
Recommendations 13
Appendices 14
1. Budget summary 15
2. Equipment and personnel 16
3. Selected seismic profiles 17
4. Core logs 24
5. Core hole locations range-range data . . . 46
6. Future core points 47
1
1
ILLUSTRATIONS
(Plates are in pocket)
Plate 1. Bathymetry map
Plate 2. Overburden thickness map
Plate 3. Shell unit thickness map
BURIED OYSTER SHELL RESOURCE EVALUATION OF THE
EASTERN REGION OF THE ALBEMARLE SOUND
by
James L. Sampair
ABSTRACT
Two hundred and sixty three miles of subbottom profiling were done in the lower Albemarle Sound,
Roanoke Sound, and Croatan Sound using a Raytheon RTT 1000, 3.5 Khz "pinger". This was followed by a
core program using an Alpine Geophysical 20 foot "Vibra Core". Sixty cores were taken at tie points
and on sedimentary structures indicated by the geophysical profiles.
Three broad areas of interest were defined for the presence of buried shell deposits, and nine
prospects are indicated on maps attached to this report. The bathymetry, the overburden thickness,
and the shell unit thickness are also indicated on the maps. Five permanent files were set up in the
Geology and Mineral Resources Section: one containing color slides of the cores taken, one containing
strip logs of the cores (consisting of color photographs with written lithologic descriptions), one
consisting of a sample file containing five cuts each of all of the cores, one containing the geo-physical
profiles, and one containing a computerized file of navigation data. There is also a 10
minute, 16mm film of the various elements of the field operation on file with the Division of Marine
Fisheries.
As a result of this study, we estimate a potential for 30.6 million cubic yards of oyster shell
in the study area, with a current raw material market value in excess of $90,000,000.00. A one-dredge
operation would take a little over 20 years to extract these shells and would employ 90 people year
around at an average annual payroll of $900,000.00.
PURPOSE AND SCOPE
This study is the first step in a program of the Department of Natural and Economic Resources to
locate and map the calcium carbonate shell deposits in the bays, estuaries, and sounds of eastern North
Carolina. It is a principle objective of this program that both the environmental and the economic
impacts of utilizing the shell resources be understood. The area covered by this study includes lower
Albemarle, Croatan, and parts of Roanoke Sounds (see Plate 1).
The study developed suitable techniques for accurately locating shell reefs and associated sediments
by rapid reconnaissance of large marine areas at reasonable costs. A subsurface coring method was
developed for sampling and measurement of the shell deposits located during reconnaissance.
Data on thickness and type of overburden, thickness and type of shell and matrix material, and
i
lithology and sequence of the associated sedimentary sections were derived from the field techniques
utilized in this study. Data on sedimentary mineralogy, stratigraphy, sedimentary structure, and
paleontology are available from photo strip logs of the cores, color slides of the cores, cuts of the
actual core material, and seismic profiles. These materials are on file with the Geology and Mineral
Resources Section and can be used to support future geologic studies and mineral resource evaluations
as well as water-use planning studies. All data collection points are precisely located by range-range
data and by Carter Coordinate data which have been computerized.
In addition to indicating the location of the shell deposits encountered in coring, this report
provides thickness maps of both the oyster shell and overburden and a discussion of the materials,
geology, and possible environmental impacts.
ORGANIZATION AND ACKNOWLEDGEMENTS
The contractor for this project was the Department of Natural and Economic Resources. The Division
of Earth Resources and the Division of Marine Fisheries of this Department were assigned the task of
executing the contract. Mr. Stephen G. Conrad, Director of the Division of Earth Resources, had primary
responsibility for organization and administration of the project.
The author, Geologist-in-Charge of the Coastal Plains area for the Geology and Mineral Resources
Section of the Division of Earth Resources, and Mr. James Brown, Assistant Director for Marine Fisheries,
were given responsibility for the execution of the necessary studies and for reporting the results.
There are many people whose efforts resulted in the timely completion of this project. The author
would like especially to thank Loi Priddy with Marine Fisheries who was a "jack of all trades" in the
project, in particular for his work in surveying, navigation, and computer technology; Orvill Til let of
the Enforcement Division of Marine Fisheries was our very able boat captain during the geophysical
survey and also helped us whenever he could during the coring operation; Jim Tew and Fentress Mundane
of Marine Fisheries found it necessary at times to revise their plans and schedules in enforcement and
oyster rehabilitation in order to make people and equipment available to this project; and Jim Coffey,
staff geologist in the Coastal Plains area, did the photography on the cores and prepared many of the
illustrations and maps for this report. There are others in Marine Fisheries and in Earth Resources
who made substantial contributions to the drafting, manuscript, and budget management whom we would
also like to thank for their time and effort.
FIELD WORK
The field work was accomplished in two steps. A reconnaissance reflection seismic survey of the
study area and shallow coring aided in correlation of the seismic data and in testing specific
anomalies noted on the seismic profiles which were thought to be prospective shell deposits. The
volume of coring was limited by budget constraints but was sufficient to prove the method.
Subbottom Profiling
The principle constraints in deriving specifications for this part of the project were cost per
unit coverage, speed, and depth of investigation. A shallow-survey reflection seismic system seemed
to be suited for the purpose and the following systems were investigated: the E.E.G. Uniboom, the Edo
Western 7 and 3.5 Khz Transducers, and the Raytheon 3.5 Khz Transducer.
Due to the 10-foot average depth of the water, the cost of equipment, and the non-critical penetra-tion
requirement, the Uniboom was not considered in detail. Because of the water depth and the uncon-solidated
nature of the sediments to be investigated, the low frequency 3.5 Khz transducer unit was
selected as the optimum tool. Raytheon was low bidder on this equipment. Special mounting equipment
was designed by the author and Loi Priddy of Marine Fisheries so that the equipment could be installed
on an eighteen-foot boat furnished by James Tew, Chief of Enforcement of Marine Fisheries.
Navigation was the next concern. It is essential that sites from which data is acquired be located
sufficiently well so that they can be easily relocated for future work. Degree of accuracy, cost,
power requirements, ease of installation, and effective operational range were all considerations. Costs
and timely availability varied widely for this equipment. The Motorola Mini-Ranger system with an
Anadex paper tape recorder was selected on the basis of cost and service. This system served very
faithfully with an accuracy of ±10 feet out to distances of twelve miles from shore stations. Had we
also included a punch tape recorder, a savings in time and money could have been effected in the sub-sequent
computerization of the navigation data. The author was not aware early in the planning of this
project that a "Cal Comp" plotter would be part of the computer hardware available to the program from
North Carolina State University. Because of budget limitations, we had only considered hand plotting
the data. In order to make use of the "Cal Comp" plotter, the data from the Anadex recorder had to
be key punched. Loi Priddy and Dr. David Link of the Computer Science Department at NCSU developed
the program to convert the range-range data from the Anadex recorder to the Carter x-y coordinate
*
system and plot the boat tracks using the "Cal Comp" plotter.
The activities and location data printed on the maps (in pocket) included in this report display
the seismic survey network as plotted by "Cal Comp" plotter. One can see in reviewing the network
that an automatic pilot on the boat would have also been of considerable assistance.
The seismic equipment emits a signal at a frequency of 3.5 Khz. On the Raytheon equipment, the
impulse rate, strength, and phase are adjustable in the hope that the operator may find the combination
that best defines the sedimentary section and achieves the most satisfactory penetration. The impulses
are reflected from velocity interfaces starting with the water-bottom contact and are received by the
transducer in a recording mode. These signals are transmitted to a Raytheon recorder which is typical
of their research fathometer unit.
In very shallow water, a multiple reflection of the water-bottom contact appears on the record at
a depth below the contact equal to the water depth. Unfortunately, in this situation, the multiple
appears in the portion of the record that is of greatest interest to this study. Adjusting the
instruments for signal strength and timing minimizes this problem but does not eliminate it.
The results achieved from the reconnaissance survey vary from poor to very good. In part, the
variation was due to the operator's improving technique as he gained experience with the equipment and
in part to water depth and sediment type. A total of 263 profile miles of seismic lines, represented
by the boat tracks printed on the maps (in pocket), were achieved at an approximate cost of $40.00
per profile mile.
A preliminary review of the data was carried out to determine the best possible location for our
core sampling program. We determined that in addition to coring some sedimentary structures that
appeared to be shell deposits, we would need coring to tie the intersections of our seismic profiles
to determine reasonable sedimentary correlations. The lateral sedimentary facies relationships are
extremely complex.
Core Sampling
Two important constraints entered into consideration of a coring technique for this study. First,
the budget was extremely limited for this sort of work which is quite expensive to do even on land.
Second, we presumed that dredging, because of the environmental hazards, would be limited to depths of
thirty feet or less. The author realizes there may be considerable controversy on this point; however,
such a limitation would have been necessary in any event in order to get any appreciable tie data for
the seismic data, given the budget constraints.
There are basically only two ways this coring could be done. The first method would be to employ
a drilling machine equipped with core barrels mounted on a barge that could be anchored in a very
stable manner both horizontally and vertically. Because of the mobility of the water and the penchant
for the winds and weather to change drastically over very short periods of time (15 to 20 minutes on
occasion), this method is very costly in relation to the amount of coring that can be accomplished. A
second method of coring is to drive coring tubes with a hammer using a barge as a platform. Among the
specific methods for doing this is a device developed by Alpine Geophysical Company called the "Vibra
Core". In this method a steel tube containing a plastic liner is mounted in an aluminum frame. An air
hammer device is mounted on the steel tube in such a way as to allow the tube to be driven into the
bottom. The tremendous advantage of this device is that the unit can be operated over the side of a
barge without anchoring the barge. The unit is picked up by a crane and set over the side on the
bottom. Air lines connected between the barge and the air hammer and a cable attached between the
barge and the coring device are the only connectors between the two. This allows as much as 100 feet
of lateral movement by the barge, and common vertical movement of the barge is not disruptive. The
principal limitation of the device is the length of core that can be taken. Alpine builds this unit
with 20 ft., 30 ft., and 40 ft. core barrels. A second limitation is the fact that during the coring
operation, the sediments can sometimes pack in such a way as to lock in the barrel. The operation will
not secure a full core in this situation. Also, when a lithology is encountered that is too indurated
to be penetrated, such as a limestone or a well-cemented sandstone, incomplete coring of the section
results. In unconsolidated sediments of the type normally found in shallow marine environments and
where the requirements are for data in the top 40 feet, this device is clearly the best answer.
During our operation, a converted ferry boat, which is used regularly by Marine Fisheries in their
oyster rehabilitation program, was provided by Mr. Fentress Mundane, the Director of that program, as our
working barge. A 30 B crane was loaded on the barge together with a 900 CFM compressor and 5 KW generator.
A 20-foot "Vibra Core" was leased from Alpine Geophysical Company and two of their operators were pro-vided
as a part of the lease package. For navigation the Motorola Mini-Ranger was used.
As can be seen on the maps (in pocket), we attempted to locate the core sites at the tie points
and on the ends of seismic lines as well as at points where shell was suspected. The mini-ranger
makes precise relocation possible; however, because of high priority of time, we settled for
i
approximate relocation in most cases rather than spend time maneuvering the barge for an exact
relocation. A total of sixty cores were taken totaling approximately 1000 feet of core at a cost of
approximately $20.00 per foot.
OFFICE AND LABORATORY WORK
The data acquired from the seismic survey are presented in the form of a continuous record section.
The vertical scale of the section is in feet and the horizontal scale is related to feet indirectly by
means of position marks which were recorded on the record sections and the navigation data. These
position marks were plotted on the record sections so that all of the seismic data can be located on
the ground with considerable precision (±3 feet). The appendices contain some examples of the seismic
data in the vicinity of located shell deposits. All the seismic data are on permanent file in the
Geology and Mineral Resources Section of the Division of Earth Resources and may be reviewed by con-tacting
the Section.
The cores were retrieved in plastic barrels that are 20 feet long and 3.5 inches in diameter. For
ease in handling, the cores were cut into 3 foot lengths. In the laboratory these 3 foot sections were
split lengthwise with a diamond saw and were then photographed and described as to lithologies and
shell content. Two types of photographs were taken: 4X5 inch color prints and 35 mm color slides.
Five cuts of each core were then preserved in plastic bags for future studies of paleontology, sedi-mentary
petrology, and whatever other geologic studies may arise for which the data would be useful.
From those cores, in which oyster or clam shells were encountered, a large sample was taken for volume
analysis of the components in the shell section plus chemical analysis of the shell to determine the
percentage of calcium carbonate. Sample logs were hand plotted for the ten holes which indicated
possible commercial shell deposits. These logs are included with this report.
Although the color prints were not reproduced for the published report, they, along with 340
color slides, are a part of the permanent file. Both the prints and the slides are available to any
interested person for viewing at the laboratory of the Geology and Mineral Resources Section in
Raleigh. Copies can be made of all or any part of the set of color slides at additional cost.
INTERPRETATION AND RESULTS
Two steps were necessary 1n the interpretation of the subbottom profiling data. Prior to the
coring operation, the profiles were reviewed in some detail to determine if sedimentary structures seen
on the profiles could be interpreted as shell beds. We assumed that the shell would present a very
hard, seismically fast layer which would generate a reflection on the profiles. To aid this determina-tion,
we had some core data which had previously encountered shell. We picked 94 sedimentary structures
in this manner and located 200 coring sites. The maps included with this report indicate the location
of interesting sedimentary structures noted during this analysis which we did not core, as well as the
location of 60 core holes.
Upon completion of the coring and analysis of the lithology, the core data was plotted on the
seismic profiles. The intervals in which shell material was encountered were then correlated on the
seismic profiles in an attempt to establish the lateral extent and thickness of the deposit. We were
somewhat frustrated in this attempt by the fact that bedding of any sort has a very erratic lateral
extent in the upper twenty feet of sediment in this area. We were unable to correlate any unit further
than a mile without substantial changes in lithology. This suggests very rapidly shifting sedimentary
environments with changing rates of depositional energy. The range of clastic sediment sizes and types
testify to open bay, stream channel, back bay, beach, and deltaic regimens in areas that are now all
open bay. These paleoenvironments are all represented in the top 15 feet of sediment.
Because it is impossible to contract for this type of coring on other than some sort of cost plus
basis and because the budget was very limited, we designed the coring program so that we could suspend
operations when the money ran out. That situation occurred after ten days of operation, during which
we secured 60 cores.
Ten of the cores that were taken encountered 1 foot or more of shell material. Each of these
sites, after review of the seismic data, were mapped for bathymetry, overburden thickness, and shell
thickness. Since the oyster shell unit exhibited more continuity across the study area, it was the
unit which was mapped and from which reserves were calculated. The scattered clam shells and shell
hash were not mapped. The shell isopach maps included with this report show the oyster shell thickness
at each of these core sites. As the maps indicate, there are three broad areas of interest designated
A, B, and C. Within these areas there are nine shell prospects. One through five are in Area A, six
is in Area B and seven, eight and nine are in Area C. Core logs included with this report as Appendix I
contain a description of the lithology, a sieve analysis of the shell sections, and an acid test of the
shell to give an approximation of the CaC0
3
content where the shell was thick enough to be commercial.
Area A
Prospect 1 - Haulover Point
In this area 3 cores were taken that encountered 1 foot or less of clay with scattered oyster
I
shells. The volume encountered was not commercial; however, the area warrants more coring. Three
core logs, numbers 42, 43, and 44, in Appendix 4 describe the sedimentary section. No screening
or other laboratory tests were carried out on samples from this site.
Prospect 2 - Peter Mashoes Creek
Substantial shell was encountered in this area in five cores, numbers 38, 39, 40, 55, and 57.
There are actually two shell banks in this area; one consists of oyster shells in a clay matrix, and
the other contains clam shells in a sand matrix. As stated previously, the oyster shell unit was
more contiguous and was the unit mapped. In a 2 mile long by 3000 foot wide area, there is a
potential for 8,960,000 cubic yards of oyster shells which averages 99.5% Ca^. The site needs addi-tional
coring to determine the precise shell reserves. The shell occurs in the top 10 feet of sedi-ment
and dredging would require some sediment control since the shell occurs in a plastic clay matrix
which would present some settling problems. Using a fairly coarse screen, perhaps 1/4" mesh, would
minimize the problem since the clay would not be completely disintegrated in this process (see dis-cussion
on dredging and the environment).
Prospect 3 - Collington Shoals
Shell was encountered in three cores, numbers 58, 59, and 60, which indicate an area of about 3
square miles containing an average of one foot or less of shell in a clay section 4.5 feet thick. The
section is in the top 6 feet of sediment. The matrix is the same as in prospect 2, and the comments
regarding dredging also apply here. The reader should also understand that since everything but the
shell is returned to the sound bottom, no substantial change in water depth is likely to result from
dredging this shell body. We can estimate a potential of 15,000,000 cubic yards of shell in this area.
Prospect 4 - Mashoes Light
Core number 35 had about 1.1 feet of oyster shell, all within the clay section. This by itself is
not commercial. However, shell occurs in a plastic clay unit throughout this area, and the clay unit is
5.4 feet thick in this core. Additional coring in the vicinity of this core should reveal a thicker shell
section. The seismic profile, line 4W, indicates that there is clay with possible shell 1,430 feet
along the profile. No laboratory testing was done on this core.
Prospect 5
Three cores encountered oyster shell in this area, 28, 30, and 52. Seismic profile 2W indicates the
possibility that the oyster shell unit may be continuous from core hole 58 in prospect 3 to core hole
28 in this prospect. That is, the clay bed that the shell occurs in could be continuous. The amount
of shell present must be determined by additional coring. We can say that everywhere along the line
that a core was taken at least 1 foot of oyster shell was encountered, and those shells overlay a
coarse sand unit that contains shell hash and clam shells. The southern portion of the area covered
by this prospect has an oyster shell potential of 3,000,000 cubic yards, not counting the clam shells.
There is also sand and gravel in this prospect which was not evaluated.
As elsewhere, the oyster shells occur in a clay matrix which in this case is 4 to 9 feet thick.
Shells are generally scattered throughout this unit but may be locally concentrated. It should be noted
that while shell nearly always occurs in relationship with the shoal areas in the sound, the deposits are
by no means restricted to these areas. The CaC0
3
solubility test reveals the oyster shells to be 94%
to 96% CaC0
3 , and the clam shell material to be about 80% CaC0
3
-
Area B
Prospect 6 - Croatan Channel
This prospect lies between channel marker "13" and "11" about 70 yards west of the channel marked
on USC and GS chart 1229. One core, number 14, located at the intersection of seismic profiles S and V
encountered the clay unit at 1.7 feet and cut 7.3 feet of clay with 3.0 feet of oyster shells. Approxi-mately
19.6% (or 0.6 feet) of the interval is shell. The CaCO solubility test indicates the shell to
be 98.6% CaC0
3
. Review of lines S and V indicates the deposit is approximately 500 feet wide in the
east-west direction and 2000 feet long along line V. The potential is about 160,000 cubic yards. The
seismic profiles show indications east and west of profile V where additional coring could prove productive.
Area C
Prospect 7 - Croatan Sound Marker "21
This prospect lies on the east side on the Croatan Channel between marker "19" and "21" on the USC
and GS chart 1229. The shell unit is encountered in core hole number 12 at 1.7 feet and extends to 2.2
feet. Seismic profile V indicates the unit may extend approximately 2000 feet north-south. Previous
coring done in the vicinity by Langenfelder Associates indicates the unit is widely present in the area,
I
particularly south to prospect 9. Additional coring will be necessary in order to estimate the full
shell potential (see discussion on prospect 9).
Prospect 8 - Position Mark "23"
This site must be located with the navigation data. Position mark "23" can be found on seismic
profile U and core hole number 8 is just south of the position mark on line U. This core hole penetrated
20 feet of clay and very fine sand typical of the oyster shell unit. Oyster shells were encountered in
the core from 17.2 feet to the bottom of the hole, and we had not penetrated below the oyster shell bear-ing
unit at that point. About 13% of the section is oyster shell containing 94.9% CaCO^. The seismic
profile indicates that the unit is continuous southward for another 2000 feet. There are also indications
of areas worthy of additional coring northward along line V. We can estimate a minimum potential in the
vicinity of core hole number 8 of 230,000 cubic yards of oyster shells.
Prospect 9 - Cedar Bush Bay
Core hole number 11 in this study and five core holes drilled by Langenfelder Associates encountered
an average of 2 feet of shell in a clay section approximately 6 feet thick. In core hole number 11 the
shell unit starts at 0.9 feet and extends to 3.3 feet. The section is approximately 23.6% shell which
contains 97.5% CaC0_. Additional coring needs to be done to outline all of the reserves in this area.
We estimate the shell potential at 1,200,000 cubic yards.
DREDGING AND THE ENVIRONMENT
There is a fundamental law in geology called the doctrine of uniformitarianism. This doctrine says
that the key to the study of past physical processes is the observation of present physical processes.
If this dictum is reversed in the present study, a very important conclusion can be reached. That is,
any attempt at preservation in the marine areas under study is doomed to certain failure with time. This
statement applies to attempts to preserve one area as fresh water or another as saltwater. It applies to
attempts to preserve bathymetry. It applies to attempts to preserve marsh in one area and open water in
another. The certain lesson to be learned from a review of the top 20 feet of sediments in the bottom of
10
the sound is that rapid change is the rule here, most certainly not the exception. What we may consider
of economic or aesthetic importance today is not to be handed down to future generations in the present
form. The natural processes that rule this area are marshalled in opposition to the status quo. A mere
6 foot rise in sea level would virtually rewrite the face of the entire area. Such movements have
occurred continuously over the past few thousand years as is indicated by the sediments recovered in this
study. Much more recently, Currituck and Albemarle Sounds were saltwater bodies year around fed not only
by Oregon Inlet but also by an inlet in the vicinity of Corolla. It was during this period that the shell
deposits currently under investigation were formed.
The present water depth throughout the area averages less than 10 feet. With the very large open
expanses available to the wind, such a shallow water environment will stir and constantly move bottom
sediments. The water will be very turbid during bad weather. Salinities will and do vary widely with
wind and with seasonal runoff brought into the sounds by the rivers. Seasonal water temperature changes
are also the norm. All of these factors suggest that the marine biota that subsist here are very flexible
and that man's activities can, at most, temporarily influence only a minor portion of the system
detrimentally.
Generally speaking, the following catagories of subjects bear on a marine ecosystem: physical
aspects - salinity, bathymetry, currents, turbidity, and temperature; biology - varieties of fish, benthic
and foraminiferal invertebrate biota, water fowl, and the food chain (plant and animal); chemistry -
chlorinated hydrocarbons in organisms and sediment column, pesticides, PCB and trace metals in sediment
column, and contained water; geology - type and distribution of sediments and sedimentary structures; and
economics - the economics of shell dredging versus the economic hazards to fish and marine biota nurseries,
to sports and commercial fishing, to water recreation, or other economic or aesthetic use of the water
environment.
To keep the discussion from evolving into a discourse on marine biology and physical oceanography,
the subjects will be dealt with in terms of dredging. This is an alternative to the baseline approach
which is recommended when an entire area is subject to environmental change and there is to be an attempt
to monitor the direction and rates at which change is occurring.
The process of dredging for shell involves cutting into the bottom of the sound to some predetermined
depth, sucking the sediments up by use of large pumps, discharging the gross pumpage across screens, and
returning to the sound bottom all but the shell of predetermined size. The discharge back to the sound
is by gravity settling.
11
Physical Effects
Dredging could affect salinity in three ways. The material being cut into could contain large per-centages
of NaCl . If the bathymetry is substantially changed, currents of saline water could encroach
I
into areas where they would not normally go. Finally, the dredge could encounter a fresh or salt water
acquifer under a clay seal with positive pressure. We can say with certainty that none of these con-ditions
will be met in the areas so far studied.
Water depth can be substantially changed as a result of dredging. However, in the area under study
the concentration of shells suggests that the normal total change will be no more than 2 feet.
Dredging has only a nominal effect on current as in the case of transgressing salt water. However,
it is important to know the current patterns in an area for different cases of wind, tide, and river
discharge in order to predict any adverse siltation effects brought about by dredge discharge.
Turbidity looms as a problem in the study area primarily because the oyster shell deposits were
all associated with a matrix of plastic clay and very fine-grained quartz sand. Considering the
relatively small area a dredge can cover as opposed to the turbidity caused in this area by a high wind
and the obvious additional fact that the biologic environment has adapted to considerable turbidity
because of the natural processes at work in the area, the logical conclusion is that any damage done by
dredging will be local and temporary for most of the study area. Marsh area would have to be given very
special attention, however, since both marine biota and water fowl depend on the marsh environment, and
even temporary destruction would have some disastrous short term economic impacts.
Biological Effects
Fin fish can be affected in two ways by dredging: first by an increase in turbidity and second by
a possible disruption of their normal food supply. The local nature of dredging normally causes only a
change in fish habitat during the dredging operation. These statements are also true for benthic biota
which can move to avoid the dredge and return when favorable conditions are re-established. Bottom
dwelling organisms which are an important element in the food chain are destroyed by dredging and
normally require two or three years to re-establish themselves provided bottom conditions have not been
so altered as to make that impossible. Great care needs to be exercised in determining areas to be
dredged so as to minimize this hazard. Areas with substantial plant food for water fowl also need to be
avoided or the plant regimen needs to be re-established after dredging.
12
A lot of rhetoric has been offered regarding the potential danger of resuspending sediments that
may contain chemicals adverse to the biota. A number of cores, particularly clays, contained connate
water with hydrogen sulfide gas. If released in sufficient amounts, this gas could be chemically
adverse to the biota, but this would require a rather massive resuspension not contemplated by shell
dredging.
As was mentioned in the section dealing with interpretation of data, the oyster shell material is
contained in a matrix of plastic clay and very fine-grained quartz sand. This is typical of a deposi-tional
environment with a very low energy level. The shell units frequently overlay a coarse sand and
shell hash unit which is typical of a forebeach environment. The overburden, if any occurs, is usually
clay or fine sand. Typically, the clay material is a stiff to very plastic material which does not
easily disintegrate in water. It is our opinion that screen sizes will be important in reducing
turbidity with this clay in any dredging operation.
Based on data obtained by the Army Corps of Engineers in environmental impact statements on San
Antonio Bay in 1971, one dredge can produce approximately 1,500,000 cubic yards of shell per year with
a value of approximately $3,000,000.00. The operation would employ the services of about 90 people, 32
barges, and 8 tug boats. The average annual payroll would amount to $710,000.00. The material is valued
as a source of chemical grade lime, as poultry grits, and as oyster clutch material. It also can be used
to manufacture portland cement. The foregoing is offered in the environmental section of this report
because it is needed to compare the value of alternative resources.
RECOMMENDATIONS
The next logical step would be a closely supervised test dredging project. We recommend the Cedar
Bush Bay Area as a good place to conduct such a test. Prior to testing, base line data should be
gathered at the site so that the area can then be monitored for any adverse environmental impacts.
Particular attention should be given to the possible adverse effects of siltation and turbidity.
We further recommend that additional funds be sought to complete the coring program in this area.
The data should be reviewed not only for shell but for a sand and gravel inventory. Substantial gravel
deposits were noted during this study. Since the northeastern section of North Carolina is in very
short supply of these commodities, the feasibility of extracting these materials at the same time as the
shell needs to be evaluated.
13
APPENDICES
14
APPENDIX 1: BUDGET SUMMARY
CPRC Funds
Lease and rental of equipment, travel expenses, and purchase of expendable supplies
through June 30, 1975 $ 8,498.00
Lease and rental of equipment, travel expenses, and purchase of expendable supplies
and equipment through June 30, 1976 26,502.00
TOTAL $35,000.00
North Carolina Department of Natural and Economic Resources Funds
1. Through June 30, 1975
Division of Earth Resources $ 4,679.44
Division of Marine Fisheries 3,444.60
TOTAL $ 8,124.04
2. Through June 30, 1976
Division of Earth Resources $12,886.21
Division of Marine Fisheries 9,359.15
$30,369.40
15
APPENDIX 2: EQUIPMENT AND PERSONNEL
1. Geological and geophysical field and interpretive personnel and equipment.
a) Two geologists and one geologic technician as needed. Two technicians, part time, as needed.
(Division of Earth Resources)
b) RTT-1000 Raytheon 3.5 Khz subbottom profiler on lease from Raytheon Corporation.
c) Alpine Geophysical Company 20 foot "Vibra Core" and two technicians on lease from Alpine
Geophysical Company.
d) Crane, 900 cfm air compressor and miscellaneous equipment on lease from Waff Brothers Heavy
Equipment Company.
2. Navigation, boat location, survey personnel and equipment.
a) A registered surveyor and one technician. (Division of Marine Fisheries)
b) Range-range boat positioning equipment, the Motorola Mini-Ranger, on lease from Motorola
Corporation.
3. Boat operators, boats and barges, as needed.
a) One seventeen foot and one fifteen foot boat as needed with operator. (Enforcement Division
of Marine Fisheries)
b) One self-propelled barge with a 3 man crew as needed in the coring operation, (oyster
rehabilitation program of Marine Fisheries)
4. Computer technology and hardware to handle the navigation data.
a) One computer specialist from Marine Fisheries and two program analysts on contract from the
Computer Science Department of North Carolina State University as needed to convert range-range
data to x-y coordinate data and plot the boat tracks using the "Cal Comp" plotter.
5. Marine biology and physical oceanography, as needed. (Division of Marine Fisheries)
6. Administrative support was provided by each Division handling records and invoices for personnel
and equipment furnished for the project. Mrs. Myrtle Tyson handled budget management on behalf of
Mr. Stephen Conrad.
16
APPENDIX 3: SELECTED SEISMIC PROFILES
17
6
to
APPENDIX 4: CORE LOGS
24
SEA LEVEL AREA C PROSPECT 8
-10-Wo
dark- to light-gray, plastic clay
-20 -E=
11.0'
12.0'
very fine-grained sand with some clay
plastic clay with fine-grained sand
30
17.2' .
18.0' 1|
20.0* JS
clay with sand and oyster shell
as above
-40
Note: The core was not deep enough to evaluate total shell
thickness, so the seismic interpretation of a total
of 7 feet was used.
Shell Unit Screen Analysis
Screen Size Sample WT . Percent
.1574" 71.2 gms 13.1%
.0787 8.7 1.6
.0394 19.9 3.7
.0197 60.3 11.1
.0098 141.8 26.0
.0098> 243.1 44.5
The commercial shell was retained on the
0.1574" screen. These were oyster shells,
A 20% HC1 solution digested 67.6 gms or
94.9% and left a residue of 3.6 gms or
5.1%.
The estimated 7 foot segment analyzed
contained .92 foot of shell.
SEA LEVE L
BOTTOMf o
0.9'
10
-20-;
30-
-40
5.7'
9.4'
15.0'
CORE NUMBER 11
AREA C PROSPECT 9
dark plastic clay
very fine-grained sand with clay and oyster shells
as above
as above with clay increasing
very fine- to fine- to medium-grained sand; grading downward
coarse-grained sand-gravel
Shell Unit Screen Analysis
Screen Size Sample MT. Percent
.1574" 127.0 gms 23.6%
.0787 15.4 2.9
.0394 17.5 3.3
.0197 46.0 8.6
.0098 149.4 27.8
.0098> 182.9 33.8
The commercial shell was retained on the
0.1574" screen. These were oyster shells.
A 20% HC1 solution digested 123.8 gms or
97.5% and left a residue of 3.2 gms or
2.5%.
The 2.4 foot segment analyzed contained
0.57 foot of shell.
26
SEA LEVEL
CORE NUMBER 12
AREA C PROSPECT 7
llOTTOM
-10 -
o
1.7
2.2
].
very fine- to fine-grained sand with some clay
shell unit as above with oyster shell
-20 -
-30 -
-40
13.0
very fine- to fine-grained sand with some clay
27
SFA LEV 1
LUKL IWIBLK 14
AREA B PROSPECT 6
-10 -
IDHQII o
1.7'
3.0'
z20
-30 -
15.0'
17.6'
fine- to medium-grained sand with some clay
very fine-grained sand with clay; minor shell
dark plastic clay; scattered shells
as above with oyster shells
as above
dark plastic clay
very fine- to fine-grained sand with clay
fine- to medium- to coarse-grained sand
as above
-40
Shell Unit Screen Analysis
Screen Size Sample WT. Percent
.0787" 105.7 qms 19.6%
.0394 9.1 1.7
.0197 4.5 0.8
.0098 22.3 4.1
.0049 187.8 34.8
.0049> 211.0 39.0
The commercial shell was retained on the
0.0787" screen. These were oyster shells.
A 20% HC1 solution digested 104.2 gms or
98.6% and left a residue of 1.5 gms or 1.4%.
The 3.0 foot segment analyzed contained
0.59 foot of shell.
28
n
SEA LEVEL
CORE NUMBER 23
AREA A PROSPECT 5
-10-
liOTTOI
3.8'
very fine-grained sand with clay and few shells
as above with scattered oyster shells
20 -r
9.4' J £
as above with oyster shells
15.2'
30
-40
very fine-grained sand with clay
29
SEA LEVEL AREA A PROSPECT 5
imw<\
-10
plastic clay
6.7'
7.7' plastic clay with oyster shell
-20-1 fine- to medium-grained, gray to yellow, quartz sand
15.2'
-30
-40
30
SEA LEVEL
-10
ijfiTTOn
-20-
30-
-40
3.0'
4.3
5.4 3s
12.0'
CORE NUMBER 35
AREA A PROSPECT 4
very fine-grained sand with some clay
dark plastic clay
dark plastic clay with some oyster shell
very fine- to medium-grained, light-gray sand; some coarse-grained
layers
31
SEA LEVEL
CORE NUMBER 38
AREA A PROSPECT 2
-10
-20
-40
\0TT0
2.2'
3.0'
3.5'
4.6'
6.0'
6.8'
9.0'
9.9'
dark plastic clay
| fine- to medium-grained sand; minor shell
? n clay with fine-grained sand; some oyster shells
% very fine- to medium-grained sand with clam shells
fine- to medium-grained sand with abundant clam shells
as above
medium- to coarse-grained, gray sand
medium- to coarse-grained, yellow-tan sand
Shell Unit Screen Analysis
Screen Size Sample WT . Percent
.1574" 263.6 gms 48.6%
.0787 27.7 5.1
.0394 26.4 4.9
.0197 65.1 12.0
.0098 119.7 22.1
.0098> 39.9 7.3
The commercial shell was retained on the
0.1574" screen. These were clam shells.
A 20% HC1 solution digested 255.8 gms or
97.1% and left a residue of 7.8 gms or 2.9%.
The 0.5 foot segment analyzed contained
.24 foot of clam shells. The analyzed
section was not the oyster shell unit and
therefore was not mapped as reserves.
32
SEA LEVEL
CORE NUMBER 39
AREA A PROSPECT 2
-10-™TTOM
very fine- to fine-grained sand with clay
4.6'
6'
6.6'
8.3 1
very fine- to fine-grained sand
dark plastic clay with some sand and oyster shells
as above
very fine-grained sand with some clay
-20-
medium- to coarse-grained sand with shell hash
13.6'
30 -
-40
Shell Unit Screen Analysis
Screen Size Sample WT . Percent
.1574" 98.8 gms 18.3%
.0787 15.8 2.9
.0394 13.7 2.5
.0197 8.2 1.5
.0098 112.2 28.8
.0098> 290.0 46.0
The commercial shell was retained on the
0.1574" screen. These were oyster shells.
A 20% HC1 solution digested 96.6 gms or
97.8% and left a residue of 2.2 gms or 2.2%.
The 2.0 foot segment analyzed contained
0.37 foot of shell.
33
SEA LEVEL
-10 -i
1 10TT0. 1
o
2.3 1
4.6'
f 6.7'
20—
30 -
40
9.5'
12.8'
15.3
15.8'
CORE NUMBER 40
AREA A PROSPECT 2
dark plastic clay
very fine- to fine-grained sand
dark plastic clay
dark plastic clay with oyster shells
very fine- to fine-grained sand with clay
coarse-grained, yellow-brown gravel
coarse-grained, dark-brown gravel with shell hash
34
SEA LEVEL
10 -
iionnii
^^-±-i 1.6'
-20 -
4.7'
7.2'
30
-40
14.1
LUKt NUPlBtK 41
AREA A PROSPECT 1
fine- to medium-grained sand
dark plastic clay
very fine- to fine-grained sand
coarse shell hash with coarse-grained sand
35
q SEA LEVE L
-in
-20
ISfflQ
-30-
-40
6.6 1 ,1
7.T 3!
IT
13.1
CORE NUMBER 42
AREA A PROSPECT 1
very fine-grained sand
as above with shell fragments
very fine-grained sand with clay and oyster shells
fine-grained, light-gray sand
coarse-grained sand with wood fragments
36
SEA LEVEL
-10
BOTTOM n
-20
-30-
-40
0.5' -
1.1'I 3:
11.4'
16.9'
COPE NUMBER 43
AREA A PROSPECT 1
very fine-grained sand with clay
as above with shell
very fine-grained sand with few shells and some clay
coarse shell hash with coarse-grained sand
37
SEA LEVEL
10-
-20 -fc
IlOTTO
-30
o
1.0'
2.0'
T^TTTT^ 18.0' mm i8.9'
-40
CORE NUMBER M
AREA A PROSPECT 1
very fine-grained sand with some clay
as above with shell
very fine-grained sand with some clay; shell increasing with depth
medium-grained, gray-yellow sand
38
SEA LEVEL
-10
CORE NUMBER 51
AREA A PROSPECT 5
lIpTTOHn
-20
-30
-40
9'
12.6'
13.6'
15'
16'
very fine-grained sand with clay
dark plastic clay
very fine-grained sand with clay
very fine- to fine-grained sand
very fine- to fine-grained sand with shell hash
as above
as above
Shell Unit Screen Analysis
Screen Size Sample WT. Percent
.0787" 102.9 gm 19.5%
.0394 72.4 13.7
.0197 216.7 41.1
.0098 107.4 20.4,
.0049 21.3 4.0
.0049> 6.8 1.3
The commercial shell was retained on the
0.0787" screen. These were clam shells.
A 20% HC1 solution digested 60.1 gms or
79.1% and left a residue of 42.8 qms or
21%.
The 3.4 foot segment analyzed contained
.66 foot of shell. The analyzed section
was not the oyster shell unit and there-fore
was not mapped as reserves.
39
SEA LEVEL
-10
20
-30-
3.0'
3.7'
6.0'
8.2'
-40
14.4'
KJKt NUHBtK bZ
AREA A PROSPECT 5
very fine- to fine-grained, tan-gray sand with some shell
very fine- to fine-grained sand with clay
very fine- to coarse-grained sand with dark plastic clay and
oyster shells
fine-grained sand
fine- to medium- to coarse-grained sand with gravel
Shell Unit Screen Analysis
Screen Size Sample WT. Percent
.1574" 160.7 gms 29.8%
.0787 24.2 4.5
.0394 32.5 6.0
.0197 57.4 10.6
.0098 87.4 16.2
. 0098 > 177.4 32.9
The commercial shell was retained on the
0.1574" screen. These were oyster shells
A 20% HC1 solution digested 151.1 gms or
94% and left a residue of 9.6 gms or 6%.
The 2.3 foot segment analyzed contained
0.68 foot of shell.
40
SEA LEVEL
CORE NUMBER 55
AREA A PROSPECT 2
-10 -
norm
r^r-
3.0'
4.0'
6.0'
7.4'
10.0'
11.0'
very fine-grained sand and plastic clay with minor clam shells
dark plastic clay
dark plastic clay, fine-grained sand with oyster shells
as above
dark plastic clay, fine-grained sand
medium- to coarse-grained sand with gravel
-30-
40
16.1
fine- to medium-grained sand, interbedded yellow-tan-gray-black layers
Shell Unit Screen Analysis
Screen Size Sample WT . Percent
.1574"
.0787
.0394
.0197
.0098
.0098>
154.7 gms
13.8
13.8
15.2
22.2
199.0
37.0%
3.3
3.3
3.6
5.3
47.5
The commercial shell was retained on the
0.1574" screen. These were oyster shells.
A 20% HC1 solution digested 153.2 gms or 99%
and left a residue of 1.5 gms or 1%.
The 3.4 foot segment analyzed con-tained
1.26 feet of shell.
41
SEA LEVEL
CORE NUMBER 57
AREA A PROSPECT 2
-10-
IIOTTOM
-20
-
:
2.T ^
3.0'
6.0'
8.2'
9.0'
.mmm 12.0'
•30-
-40
dark plastic clay
as above with some sand and oyster shells
as above
as above
fine- to medium-grained sand with clay; some shells
fine- to medium-grained sand
Shell Unit Screen Analysis
Screen Size Sample WT . Percent
.1574" 187.8 gm 36.7%
.0787 14.2 2.8
.0394 12.1 2.4
.0197 20.5 3.9
.0098 2.6 0.5
.0098> 275.0 53.7
The commercial shell was retained on
the 0.1574" screen. These were oyster
shells. A 20% HC1 solution digested
186.8 gms or 99.5% and left a residue
of 1.0 gms or 0.5%.
The 6.1 foot segment analyzed contained
2.24 feet of shell.
42
SEA LEVEL
CORE NUMBER 58
AREA A PROSPECT 3
IlOTTOII
-10-
o
1.2'
3.6'
very fine-grained sand
very fine-grained sand with oyster shells
10.0'
-20
-30-
-40
fine-grained sand with clay, some shell
43
SEA LEVEL
-10
-20
4.8'
7.T
8.1'
12.
9
1
CORE NUMBER 59
AREA A PROSPECT 3
fine- to medium-grained sand
dark plastic clay with sand
plastic clay with oyster shells
fine- to medium-grained sand with shell hash
-30
40
44
SEA LEVEL
toiwo
10
-20-
W2.
30
W
1.8'
3.0 1
4.6'
6.0'
7.7'
10.7'
13.4'
14'
CORE NUMBER 60
AREA A PROSPECT 3
very fine- to fine-grained sand
as above with scattered shells
fine-grained sand with clay and shells
dark plastic clay; sand with oyster shells
clay as above grading to sand; no shells
medium-grained sand with minor shell
coarse-grained sand; some shell hash
coarse-grained, tan sand with shell hash
Shell Unit Screen Analysis
Screen Size Sample WT . Percent
.0787" 76.6 gms 15.6%
.0394 6.20 1.3
.0197 11.80 7.4
.0098 98.28 20.0
.0049 140.00 28.4
.0049> 149.42 32.3
The commercial shell was retained on the
0.0787" screen. These were oyster shells.
A 20% HC1 solution digested 73.3 gms or
96.1% and left a residue of 3.0 gms or 3.9%.
The 1.4 foot segment analyzed contained 0.22
foot of shell
.
45
APPENDIX 5: CORE HOLE LOCATIONS: RANGE-RANGE DATA
Core
No.
Line
Designation
West Bridge
Meters Feet
East Bridge
Meters Feet
1 Shipyard Channel Bridge
2 S-14-10 4482 14705 5746 18853
3 S-14-5 4617 15148 5260 17258
4 TV-A 6253 20516 7065 23180
5 TV -30 6394 20979 6062 19889
6 T-19 7844 25736 5875 19276
7 U-21-6 9659 31691 8130 26675
8 U-23-1 10776 35356 9581 31435
9 U-24 12010 39405 11010 36124
10 V-25-4 12535 41127 12037 39493
11 V-26 13228 43401 12909 42354
12 V-27-12 9907 32505 9907 32505
13 V-28-7 8477 27813 8430 27659
14 VS-T-31 4897 16067 4680 15355
15 VR-T-32 3885 12747 3672 12048
16 VQ-T-33 3132 10276 2710 8892
17 VP-T-34 2610 8563 2546 8353
18 V-35 2196 7205 2311 7582
19 P-5 4450 14600 1096 3596
20 Q-6 5180 16996 1956 6418
21 R-ll 5701 18705 3100 10171
22 S-13 6655 21835 4210 13813
23 P-2 1183 3881 4605 15109
24 Q-8 2220 7284 4647 15247
25 R-9 3400 11155 5106 16753
26 S-15 4572 15001 6086 19968
2 7 T-16 5893 19335 7223 23699
23 N-28-11 12701 41672 215 705
29 4WN-T 13338 43762 847 2779
30 4WM-T 13091 42952 1157 3796
31 4W-2-4 12857 42184 1800 5906
32 4WL-T-3 12857 42184 2585 8481
33 4WK-T-22 12729 41764 3148 10329
34 4WJ-T-19 12552 41183 4424 14515
35 4W-5 12580 41275 5225 17143
36 4WI-T 12655 41521 6100 20014
37 4WH-T 12884 42272 6917 22695
38 4WG-T 13316 43690 7905 25936
39 4WF-T 14030 46032 8662 28420
40 4WE-T 14837 48680 9661 31698
41 4WD-T 15466 50744 10659 34972
42 4WC-T 16221 53221 11725 38470
43 4WB-T 16920 55515 12632 41446
44 4WA-T 17285 56712 13108 43007
45 AB-T-(B-2) 17397 57080 12599 41337
46 C-5± 16312 53520 11352 37246
4 7 D-6± 15647 51338 10437 34244
4? E-9± 15142 49681 9353 30687
49 F-10+ 14501 47578 8682 28486
50 G-12-10± 14065 46147 7762 25467
51 M-26 11204 36760 1725 5660
52 L-25 11397 37394 2315 7596
53 K-21 11202 37654 3636 11930
54 J-20 11661 38260 4378 14364
55 H-15 12465 40898 7083 23239
56 G-12 12950 42489 8163 26783
57 F-ll 13508 44320 8863 29080
58 2W/1S-12+ 9607 31521 6230 20441
59 2W/2S-T-12-6 9875 32400 5002 16412
60 4S ext. 9580 31432 3510 11516
46
APPENDIX 6: FUTURE CORE POINTS
Line Designation Locat ion*
PM3 MM7
PM1 MM7
PM2
PM3 MM5
MM9
PM4 MM3
PM1 MM2
PM3 MM8
PM4 MM4
PM5 MM4
PM6 MM3
PM5 MM4
PM3 MM!
PM1 MM2
PM2 MM7
PM12
PM8 MM2
PM6 MM5
PM6 MM!
PM1 MM2
PM4 MM4
PM4 MM9
PM7
PM9 MM5
PM8
PM9
PM10 MM6
PM14 MM3
PM26 MM3
PM17 MM2
PM10 MM2
PM15
PM7 MM4
PM6 MM4
PM4 MM3
PM1 MM5
PM11 MM5
PM11
PM8
PM6 MM4
PM2 MM! 2
PM2 MM16
PM2 MM28
PM2 MM31
PM1 MM10
PM1 MM125
PM1 MM5
PM2 MM6
ne Designation Location*
IS PM1 MM17
PM1 MM8
PM1
PM1 MM3
C PM4 MM1
DE PM7 MM4
E PM8 MM!
FG PM11 MM 3
G PM12 MM2
PM12 MM6
H PM14 MM6
PM14 MM 10
HI PM15 MM5
I PM16 MM7
PM16 MM10
L PM24 MM 16
PM25 MM 3
PM26 MM3
PM26 MM8
PM26 MM10
P PM4 MM5
o. PM7 MM2
PM13 MM6
PM13 MM9
PM13 MM15
T PM16 MM6
PM17 MM3
PM17 MM5
U PM23 MM6
PM20 MM6
V PM25 MM4
PM25 MM 10
PM26 MM5
PM27 MM13
2W PM12
PM15
MM3
3W PM1 MM 7
IN shadow PM3
2N shadow PM4
PM3
MM3
4N shadow PM2 MM8
PM1 MM5
5N shadow PM1 MM11
3S ext PM7 MM3
PM1 MM5
5S ext PM3 MM6
16N
15N
14N
13N
13
12N
ION
9N
8N
7N rerun
6N
5N
4N west
3N
2N
IN
* PM refers to Position Mark and MM to Minute Mark and are so indicated on the seismic lines and ranqe-range
data.
47
SMC DEMS LIBRARY
1610 IV5SC
RALEjOK.NC 27699-1 6 1
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NORTH CAROLINA
DEPARTMENT OF NATURAL AND ECONOMIC RESOURCES
DIVISION OF EARTH RESOURCES
GEOLOGY AND MINERAL RESOURCES SECTION
RALEIGH
1976
BULLETIN 85
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BURIED OYSTER SHELL RESOURCE EVALUATION
OF THE
EASTERN REGION OF THE ALBEMARLE SOUND
NORTH CAROLINA
DEPARTMENT OF NATURAL AND ECONOMIC RESOURCES
DIVISION OF EARTH RESOURCES
GEOLOGY AND MINERAL RESOURCES SECTION
RALEIGH
1976
COVER PHOTOGRAPH SHOWS ALPINE "VIBRA CORE" BEING LOWERED
INTO THE ALBEMARLE SOUND BY MEANS OF A BARGE-MOUNTED CRANE,
Edited by: Edward R. Burt
Layout by: Benjamin J. McKenzie
Printed by: State Government Printing Office
Additional copies of this publication are available from:
Department of Natural and Economic Resources
Earth Resources Division
Geology and Mineral Resources Section
P. 0. Box 27687
Raleigh, North Carolina 27611
BURIED OYSTER SHELL RESOURCE EVALUATION
OF THE
EASTERN REGION OF THE ALBEMARLE SOUND
BY
JAMES L. SAMPAIR
IN COOPERATION WITH THE
DIVISION OF MARINE FISHERIES
M - *
... A
0»* «
GEOLOGY AND MINERAL RESOURCES SECTION
This section shall, by law ". . .make such examination, survey, and mapping of the geology, mineralogy,
and topography of the state, including their industrial and economic utilization, as it may consider
necessary.
In carrying out its duties under this law, the section promotes the wise conservation and use of mineral
resources by industry, commerce, agriculture, and other governmental agencies for the general welfare of
the citizens of North Carolina.
The Section conducts a number of basic and applied research projects in environmental resource plan-ning,
mineral resource exploration, mineral statistics, and systematic geologic mapping. Services constitute
a major portion of the Section's activities and include identifying rock and mineral samples submitted by
the citizens of the state and providing consulting services and specially prepared reports to other agencies
that require geological information.
The Geology and Mineral Resources Section publishes results of its research in its own series of Bulletins,
Economic Papers, Information Circulars, Educational Series, Geologic Maps, and Special Publications. For
a complete list of publications or more information about the Section please write: Geology and Mineral
Resources Section, P. O. Box 27687, Raleigh, North Carolina 2761 1.
CONTENTS
Page
Abstract 1
Purpose and scope 1
Organization and acknowledgements 2
Fieldwork 3
Subbottom profiling 3
Core sampling 5
Office and laboratory work , 6
Interpretation and results 7
Area A 8
Prospect 1 - Haul over Point 8
Prospect 2 - Peter Mashoes Creek 8
Prospect 3 - Collington Shoals 8
Prospect 4 - Mashoes Light 8
Prospect 5 9
Area B 9
Prospect 6 - Croatan Channel 9
Area C 9
Prospect 7 - Croatan Sound marker "21" 9
Prospect 8 - position mark 23 10
Prospect 9 - Cedar Bush Bay 10
Dredging and the environment 10
Physical effects 12
Biological effects 12
Recommendations 13
Appendices 14
1. Budget summary 15
2. Equipment and personnel 16
3. Selected seismic profiles 17
4. Core logs 24
5. Core hole locations range-range data . . . 46
6. Future core points 47
1
1
ILLUSTRATIONS
(Plates are in pocket)
Plate 1. Bathymetry map
Plate 2. Overburden thickness map
Plate 3. Shell unit thickness map
BURIED OYSTER SHELL RESOURCE EVALUATION OF THE
EASTERN REGION OF THE ALBEMARLE SOUND
by
James L. Sampair
ABSTRACT
Two hundred and sixty three miles of subbottom profiling were done in the lower Albemarle Sound,
Roanoke Sound, and Croatan Sound using a Raytheon RTT 1000, 3.5 Khz "pinger". This was followed by a
core program using an Alpine Geophysical 20 foot "Vibra Core". Sixty cores were taken at tie points
and on sedimentary structures indicated by the geophysical profiles.
Three broad areas of interest were defined for the presence of buried shell deposits, and nine
prospects are indicated on maps attached to this report. The bathymetry, the overburden thickness,
and the shell unit thickness are also indicated on the maps. Five permanent files were set up in the
Geology and Mineral Resources Section: one containing color slides of the cores taken, one containing
strip logs of the cores (consisting of color photographs with written lithologic descriptions), one
consisting of a sample file containing five cuts each of all of the cores, one containing the geo-physical
profiles, and one containing a computerized file of navigation data. There is also a 10
minute, 16mm film of the various elements of the field operation on file with the Division of Marine
Fisheries.
As a result of this study, we estimate a potential for 30.6 million cubic yards of oyster shell
in the study area, with a current raw material market value in excess of $90,000,000.00. A one-dredge
operation would take a little over 20 years to extract these shells and would employ 90 people year
around at an average annual payroll of $900,000.00.
PURPOSE AND SCOPE
This study is the first step in a program of the Department of Natural and Economic Resources to
locate and map the calcium carbonate shell deposits in the bays, estuaries, and sounds of eastern North
Carolina. It is a principle objective of this program that both the environmental and the economic
impacts of utilizing the shell resources be understood. The area covered by this study includes lower
Albemarle, Croatan, and parts of Roanoke Sounds (see Plate 1).
The study developed suitable techniques for accurately locating shell reefs and associated sediments
by rapid reconnaissance of large marine areas at reasonable costs. A subsurface coring method was
developed for sampling and measurement of the shell deposits located during reconnaissance.
Data on thickness and type of overburden, thickness and type of shell and matrix material, and
i
lithology and sequence of the associated sedimentary sections were derived from the field techniques
utilized in this study. Data on sedimentary mineralogy, stratigraphy, sedimentary structure, and
paleontology are available from photo strip logs of the cores, color slides of the cores, cuts of the
actual core material, and seismic profiles. These materials are on file with the Geology and Mineral
Resources Section and can be used to support future geologic studies and mineral resource evaluations
as well as water-use planning studies. All data collection points are precisely located by range-range
data and by Carter Coordinate data which have been computerized.
In addition to indicating the location of the shell deposits encountered in coring, this report
provides thickness maps of both the oyster shell and overburden and a discussion of the materials,
geology, and possible environmental impacts.
ORGANIZATION AND ACKNOWLEDGEMENTS
The contractor for this project was the Department of Natural and Economic Resources. The Division
of Earth Resources and the Division of Marine Fisheries of this Department were assigned the task of
executing the contract. Mr. Stephen G. Conrad, Director of the Division of Earth Resources, had primary
responsibility for organization and administration of the project.
The author, Geologist-in-Charge of the Coastal Plains area for the Geology and Mineral Resources
Section of the Division of Earth Resources, and Mr. James Brown, Assistant Director for Marine Fisheries,
were given responsibility for the execution of the necessary studies and for reporting the results.
There are many people whose efforts resulted in the timely completion of this project. The author
would like especially to thank Loi Priddy with Marine Fisheries who was a "jack of all trades" in the
project, in particular for his work in surveying, navigation, and computer technology; Orvill Til let of
the Enforcement Division of Marine Fisheries was our very able boat captain during the geophysical
survey and also helped us whenever he could during the coring operation; Jim Tew and Fentress Mundane
of Marine Fisheries found it necessary at times to revise their plans and schedules in enforcement and
oyster rehabilitation in order to make people and equipment available to this project; and Jim Coffey,
staff geologist in the Coastal Plains area, did the photography on the cores and prepared many of the
illustrations and maps for this report. There are others in Marine Fisheries and in Earth Resources
who made substantial contributions to the drafting, manuscript, and budget management whom we would
also like to thank for their time and effort.
FIELD WORK
The field work was accomplished in two steps. A reconnaissance reflection seismic survey of the
study area and shallow coring aided in correlation of the seismic data and in testing specific
anomalies noted on the seismic profiles which were thought to be prospective shell deposits. The
volume of coring was limited by budget constraints but was sufficient to prove the method.
Subbottom Profiling
The principle constraints in deriving specifications for this part of the project were cost per
unit coverage, speed, and depth of investigation. A shallow-survey reflection seismic system seemed
to be suited for the purpose and the following systems were investigated: the E.E.G. Uniboom, the Edo
Western 7 and 3.5 Khz Transducers, and the Raytheon 3.5 Khz Transducer.
Due to the 10-foot average depth of the water, the cost of equipment, and the non-critical penetra-tion
requirement, the Uniboom was not considered in detail. Because of the water depth and the uncon-solidated
nature of the sediments to be investigated, the low frequency 3.5 Khz transducer unit was
selected as the optimum tool. Raytheon was low bidder on this equipment. Special mounting equipment
was designed by the author and Loi Priddy of Marine Fisheries so that the equipment could be installed
on an eighteen-foot boat furnished by James Tew, Chief of Enforcement of Marine Fisheries.
Navigation was the next concern. It is essential that sites from which data is acquired be located
sufficiently well so that they can be easily relocated for future work. Degree of accuracy, cost,
power requirements, ease of installation, and effective operational range were all considerations. Costs
and timely availability varied widely for this equipment. The Motorola Mini-Ranger system with an
Anadex paper tape recorder was selected on the basis of cost and service. This system served very
faithfully with an accuracy of ±10 feet out to distances of twelve miles from shore stations. Had we
also included a punch tape recorder, a savings in time and money could have been effected in the sub-sequent
computerization of the navigation data. The author was not aware early in the planning of this
project that a "Cal Comp" plotter would be part of the computer hardware available to the program from
North Carolina State University. Because of budget limitations, we had only considered hand plotting
the data. In order to make use of the "Cal Comp" plotter, the data from the Anadex recorder had to
be key punched. Loi Priddy and Dr. David Link of the Computer Science Department at NCSU developed
the program to convert the range-range data from the Anadex recorder to the Carter x-y coordinate
*
system and plot the boat tracks using the "Cal Comp" plotter.
The activities and location data printed on the maps (in pocket) included in this report display
the seismic survey network as plotted by "Cal Comp" plotter. One can see in reviewing the network
that an automatic pilot on the boat would have also been of considerable assistance.
The seismic equipment emits a signal at a frequency of 3.5 Khz. On the Raytheon equipment, the
impulse rate, strength, and phase are adjustable in the hope that the operator may find the combination
that best defines the sedimentary section and achieves the most satisfactory penetration. The impulses
are reflected from velocity interfaces starting with the water-bottom contact and are received by the
transducer in a recording mode. These signals are transmitted to a Raytheon recorder which is typical
of their research fathometer unit.
In very shallow water, a multiple reflection of the water-bottom contact appears on the record at
a depth below the contact equal to the water depth. Unfortunately, in this situation, the multiple
appears in the portion of the record that is of greatest interest to this study. Adjusting the
instruments for signal strength and timing minimizes this problem but does not eliminate it.
The results achieved from the reconnaissance survey vary from poor to very good. In part, the
variation was due to the operator's improving technique as he gained experience with the equipment and
in part to water depth and sediment type. A total of 263 profile miles of seismic lines, represented
by the boat tracks printed on the maps (in pocket), were achieved at an approximate cost of $40.00
per profile mile.
A preliminary review of the data was carried out to determine the best possible location for our
core sampling program. We determined that in addition to coring some sedimentary structures that
appeared to be shell deposits, we would need coring to tie the intersections of our seismic profiles
to determine reasonable sedimentary correlations. The lateral sedimentary facies relationships are
extremely complex.
Core Sampling
Two important constraints entered into consideration of a coring technique for this study. First,
the budget was extremely limited for this sort of work which is quite expensive to do even on land.
Second, we presumed that dredging, because of the environmental hazards, would be limited to depths of
thirty feet or less. The author realizes there may be considerable controversy on this point; however,
such a limitation would have been necessary in any event in order to get any appreciable tie data for
the seismic data, given the budget constraints.
There are basically only two ways this coring could be done. The first method would be to employ
a drilling machine equipped with core barrels mounted on a barge that could be anchored in a very
stable manner both horizontally and vertically. Because of the mobility of the water and the penchant
for the winds and weather to change drastically over very short periods of time (15 to 20 minutes on
occasion), this method is very costly in relation to the amount of coring that can be accomplished. A
second method of coring is to drive coring tubes with a hammer using a barge as a platform. Among the
specific methods for doing this is a device developed by Alpine Geophysical Company called the "Vibra
Core". In this method a steel tube containing a plastic liner is mounted in an aluminum frame. An air
hammer device is mounted on the steel tube in such a way as to allow the tube to be driven into the
bottom. The tremendous advantage of this device is that the unit can be operated over the side of a
barge without anchoring the barge. The unit is picked up by a crane and set over the side on the
bottom. Air lines connected between the barge and the air hammer and a cable attached between the
barge and the coring device are the only connectors between the two. This allows as much as 100 feet
of lateral movement by the barge, and common vertical movement of the barge is not disruptive. The
principal limitation of the device is the length of core that can be taken. Alpine builds this unit
with 20 ft., 30 ft., and 40 ft. core barrels. A second limitation is the fact that during the coring
operation, the sediments can sometimes pack in such a way as to lock in the barrel. The operation will
not secure a full core in this situation. Also, when a lithology is encountered that is too indurated
to be penetrated, such as a limestone or a well-cemented sandstone, incomplete coring of the section
results. In unconsolidated sediments of the type normally found in shallow marine environments and
where the requirements are for data in the top 40 feet, this device is clearly the best answer.
During our operation, a converted ferry boat, which is used regularly by Marine Fisheries in their
oyster rehabilitation program, was provided by Mr. Fentress Mundane, the Director of that program, as our
working barge. A 30 B crane was loaded on the barge together with a 900 CFM compressor and 5 KW generator.
A 20-foot "Vibra Core" was leased from Alpine Geophysical Company and two of their operators were pro-vided
as a part of the lease package. For navigation the Motorola Mini-Ranger was used.
As can be seen on the maps (in pocket), we attempted to locate the core sites at the tie points
and on the ends of seismic lines as well as at points where shell was suspected. The mini-ranger
makes precise relocation possible; however, because of high priority of time, we settled for
i
approximate relocation in most cases rather than spend time maneuvering the barge for an exact
relocation. A total of sixty cores were taken totaling approximately 1000 feet of core at a cost of
approximately $20.00 per foot.
OFFICE AND LABORATORY WORK
The data acquired from the seismic survey are presented in the form of a continuous record section.
The vertical scale of the section is in feet and the horizontal scale is related to feet indirectly by
means of position marks which were recorded on the record sections and the navigation data. These
position marks were plotted on the record sections so that all of the seismic data can be located on
the ground with considerable precision (±3 feet). The appendices contain some examples of the seismic
data in the vicinity of located shell deposits. All the seismic data are on permanent file in the
Geology and Mineral Resources Section of the Division of Earth Resources and may be reviewed by con-tacting
the Section.
The cores were retrieved in plastic barrels that are 20 feet long and 3.5 inches in diameter. For
ease in handling, the cores were cut into 3 foot lengths. In the laboratory these 3 foot sections were
split lengthwise with a diamond saw and were then photographed and described as to lithologies and
shell content. Two types of photographs were taken: 4X5 inch color prints and 35 mm color slides.
Five cuts of each core were then preserved in plastic bags for future studies of paleontology, sedi-mentary
petrology, and whatever other geologic studies may arise for which the data would be useful.
From those cores, in which oyster or clam shells were encountered, a large sample was taken for volume
analysis of the components in the shell section plus chemical analysis of the shell to determine the
percentage of calcium carbonate. Sample logs were hand plotted for the ten holes which indicated
possible commercial shell deposits. These logs are included with this report.
Although the color prints were not reproduced for the published report, they, along with 340
color slides, are a part of the permanent file. Both the prints and the slides are available to any
interested person for viewing at the laboratory of the Geology and Mineral Resources Section in
Raleigh. Copies can be made of all or any part of the set of color slides at additional cost.
INTERPRETATION AND RESULTS
Two steps were necessary 1n the interpretation of the subbottom profiling data. Prior to the
coring operation, the profiles were reviewed in some detail to determine if sedimentary structures seen
on the profiles could be interpreted as shell beds. We assumed that the shell would present a very
hard, seismically fast layer which would generate a reflection on the profiles. To aid this determina-tion,
we had some core data which had previously encountered shell. We picked 94 sedimentary structures
in this manner and located 200 coring sites. The maps included with this report indicate the location
of interesting sedimentary structures noted during this analysis which we did not core, as well as the
location of 60 core holes.
Upon completion of the coring and analysis of the lithology, the core data was plotted on the
seismic profiles. The intervals in which shell material was encountered were then correlated on the
seismic profiles in an attempt to establish the lateral extent and thickness of the deposit. We were
somewhat frustrated in this attempt by the fact that bedding of any sort has a very erratic lateral
extent in the upper twenty feet of sediment in this area. We were unable to correlate any unit further
than a mile without substantial changes in lithology. This suggests very rapidly shifting sedimentary
environments with changing rates of depositional energy. The range of clastic sediment sizes and types
testify to open bay, stream channel, back bay, beach, and deltaic regimens in areas that are now all
open bay. These paleoenvironments are all represented in the top 15 feet of sediment.
Because it is impossible to contract for this type of coring on other than some sort of cost plus
basis and because the budget was very limited, we designed the coring program so that we could suspend
operations when the money ran out. That situation occurred after ten days of operation, during which
we secured 60 cores.
Ten of the cores that were taken encountered 1 foot or more of shell material. Each of these
sites, after review of the seismic data, were mapped for bathymetry, overburden thickness, and shell
thickness. Since the oyster shell unit exhibited more continuity across the study area, it was the
unit which was mapped and from which reserves were calculated. The scattered clam shells and shell
hash were not mapped. The shell isopach maps included with this report show the oyster shell thickness
at each of these core sites. As the maps indicate, there are three broad areas of interest designated
A, B, and C. Within these areas there are nine shell prospects. One through five are in Area A, six
is in Area B and seven, eight and nine are in Area C. Core logs included with this report as Appendix I
contain a description of the lithology, a sieve analysis of the shell sections, and an acid test of the
shell to give an approximation of the CaC0
3
content where the shell was thick enough to be commercial.
Area A
Prospect 1 - Haulover Point
In this area 3 cores were taken that encountered 1 foot or less of clay with scattered oyster
I
shells. The volume encountered was not commercial; however, the area warrants more coring. Three
core logs, numbers 42, 43, and 44, in Appendix 4 describe the sedimentary section. No screening
or other laboratory tests were carried out on samples from this site.
Prospect 2 - Peter Mashoes Creek
Substantial shell was encountered in this area in five cores, numbers 38, 39, 40, 55, and 57.
There are actually two shell banks in this area; one consists of oyster shells in a clay matrix, and
the other contains clam shells in a sand matrix. As stated previously, the oyster shell unit was
more contiguous and was the unit mapped. In a 2 mile long by 3000 foot wide area, there is a
potential for 8,960,000 cubic yards of oyster shells which averages 99.5% Ca^. The site needs addi-tional
coring to determine the precise shell reserves. The shell occurs in the top 10 feet of sedi-ment
and dredging would require some sediment control since the shell occurs in a plastic clay matrix
which would present some settling problems. Using a fairly coarse screen, perhaps 1/4" mesh, would
minimize the problem since the clay would not be completely disintegrated in this process (see dis-cussion
on dredging and the environment).
Prospect 3 - Collington Shoals
Shell was encountered in three cores, numbers 58, 59, and 60, which indicate an area of about 3
square miles containing an average of one foot or less of shell in a clay section 4.5 feet thick. The
section is in the top 6 feet of sediment. The matrix is the same as in prospect 2, and the comments
regarding dredging also apply here. The reader should also understand that since everything but the
shell is returned to the sound bottom, no substantial change in water depth is likely to result from
dredging this shell body. We can estimate a potential of 15,000,000 cubic yards of shell in this area.
Prospect 4 - Mashoes Light
Core number 35 had about 1.1 feet of oyster shell, all within the clay section. This by itself is
not commercial. However, shell occurs in a plastic clay unit throughout this area, and the clay unit is
5.4 feet thick in this core. Additional coring in the vicinity of this core should reveal a thicker shell
section. The seismic profile, line 4W, indicates that there is clay with possible shell 1,430 feet
along the profile. No laboratory testing was done on this core.
Prospect 5
Three cores encountered oyster shell in this area, 28, 30, and 52. Seismic profile 2W indicates the
possibility that the oyster shell unit may be continuous from core hole 58 in prospect 3 to core hole
28 in this prospect. That is, the clay bed that the shell occurs in could be continuous. The amount
of shell present must be determined by additional coring. We can say that everywhere along the line
that a core was taken at least 1 foot of oyster shell was encountered, and those shells overlay a
coarse sand unit that contains shell hash and clam shells. The southern portion of the area covered
by this prospect has an oyster shell potential of 3,000,000 cubic yards, not counting the clam shells.
There is also sand and gravel in this prospect which was not evaluated.
As elsewhere, the oyster shells occur in a clay matrix which in this case is 4 to 9 feet thick.
Shells are generally scattered throughout this unit but may be locally concentrated. It should be noted
that while shell nearly always occurs in relationship with the shoal areas in the sound, the deposits are
by no means restricted to these areas. The CaC0
3
solubility test reveals the oyster shells to be 94%
to 96% CaC0
3 , and the clam shell material to be about 80% CaC0
3
-
Area B
Prospect 6 - Croatan Channel
This prospect lies between channel marker "13" and "11" about 70 yards west of the channel marked
on USC and GS chart 1229. One core, number 14, located at the intersection of seismic profiles S and V
encountered the clay unit at 1.7 feet and cut 7.3 feet of clay with 3.0 feet of oyster shells. Approxi-mately
19.6% (or 0.6 feet) of the interval is shell. The CaCO solubility test indicates the shell to
be 98.6% CaC0
3
. Review of lines S and V indicates the deposit is approximately 500 feet wide in the
east-west direction and 2000 feet long along line V. The potential is about 160,000 cubic yards. The
seismic profiles show indications east and west of profile V where additional coring could prove productive.
Area C
Prospect 7 - Croatan Sound Marker "21
This prospect lies on the east side on the Croatan Channel between marker "19" and "21" on the USC
and GS chart 1229. The shell unit is encountered in core hole number 12 at 1.7 feet and extends to 2.2
feet. Seismic profile V indicates the unit may extend approximately 2000 feet north-south. Previous
coring done in the vicinity by Langenfelder Associates indicates the unit is widely present in the area,
I
particularly south to prospect 9. Additional coring will be necessary in order to estimate the full
shell potential (see discussion on prospect 9).
Prospect 8 - Position Mark "23"
This site must be located with the navigation data. Position mark "23" can be found on seismic
profile U and core hole number 8 is just south of the position mark on line U. This core hole penetrated
20 feet of clay and very fine sand typical of the oyster shell unit. Oyster shells were encountered in
the core from 17.2 feet to the bottom of the hole, and we had not penetrated below the oyster shell bear-ing
unit at that point. About 13% of the section is oyster shell containing 94.9% CaCO^. The seismic
profile indicates that the unit is continuous southward for another 2000 feet. There are also indications
of areas worthy of additional coring northward along line V. We can estimate a minimum potential in the
vicinity of core hole number 8 of 230,000 cubic yards of oyster shells.
Prospect 9 - Cedar Bush Bay
Core hole number 11 in this study and five core holes drilled by Langenfelder Associates encountered
an average of 2 feet of shell in a clay section approximately 6 feet thick. In core hole number 11 the
shell unit starts at 0.9 feet and extends to 3.3 feet. The section is approximately 23.6% shell which
contains 97.5% CaC0_. Additional coring needs to be done to outline all of the reserves in this area.
We estimate the shell potential at 1,200,000 cubic yards.
DREDGING AND THE ENVIRONMENT
There is a fundamental law in geology called the doctrine of uniformitarianism. This doctrine says
that the key to the study of past physical processes is the observation of present physical processes.
If this dictum is reversed in the present study, a very important conclusion can be reached. That is,
any attempt at preservation in the marine areas under study is doomed to certain failure with time. This
statement applies to attempts to preserve one area as fresh water or another as saltwater. It applies to
attempts to preserve bathymetry. It applies to attempts to preserve marsh in one area and open water in
another. The certain lesson to be learned from a review of the top 20 feet of sediments in the bottom of
10
the sound is that rapid change is the rule here, most certainly not the exception. What we may consider
of economic or aesthetic importance today is not to be handed down to future generations in the present
form. The natural processes that rule this area are marshalled in opposition to the status quo. A mere
6 foot rise in sea level would virtually rewrite the face of the entire area. Such movements have
occurred continuously over the past few thousand years as is indicated by the sediments recovered in this
study. Much more recently, Currituck and Albemarle Sounds were saltwater bodies year around fed not only
by Oregon Inlet but also by an inlet in the vicinity of Corolla. It was during this period that the shell
deposits currently under investigation were formed.
The present water depth throughout the area averages less than 10 feet. With the very large open
expanses available to the wind, such a shallow water environment will stir and constantly move bottom
sediments. The water will be very turbid during bad weather. Salinities will and do vary widely with
wind and with seasonal runoff brought into the sounds by the rivers. Seasonal water temperature changes
are also the norm. All of these factors suggest that the marine biota that subsist here are very flexible
and that man's activities can, at most, temporarily influence only a minor portion of the system
detrimentally.
Generally speaking, the following catagories of subjects bear on a marine ecosystem: physical
aspects - salinity, bathymetry, currents, turbidity, and temperature; biology - varieties of fish, benthic
and foraminiferal invertebrate biota, water fowl, and the food chain (plant and animal); chemistry -
chlorinated hydrocarbons in organisms and sediment column, pesticides, PCB and trace metals in sediment
column, and contained water; geology - type and distribution of sediments and sedimentary structures; and
economics - the economics of shell dredging versus the economic hazards to fish and marine biota nurseries,
to sports and commercial fishing, to water recreation, or other economic or aesthetic use of the water
environment.
To keep the discussion from evolving into a discourse on marine biology and physical oceanography,
the subjects will be dealt with in terms of dredging. This is an alternative to the baseline approach
which is recommended when an entire area is subject to environmental change and there is to be an attempt
to monitor the direction and rates at which change is occurring.
The process of dredging for shell involves cutting into the bottom of the sound to some predetermined
depth, sucking the sediments up by use of large pumps, discharging the gross pumpage across screens, and
returning to the sound bottom all but the shell of predetermined size. The discharge back to the sound
is by gravity settling.
11
Physical Effects
Dredging could affect salinity in three ways. The material being cut into could contain large per-centages
of NaCl . If the bathymetry is substantially changed, currents of saline water could encroach
I
into areas where they would not normally go. Finally, the dredge could encounter a fresh or salt water
acquifer under a clay seal with positive pressure. We can say with certainty that none of these con-ditions
will be met in the areas so far studied.
Water depth can be substantially changed as a result of dredging. However, in the area under study
the concentration of shells suggests that the normal total change will be no more than 2 feet.
Dredging has only a nominal effect on current as in the case of transgressing salt water. However,
it is important to know the current patterns in an area for different cases of wind, tide, and river
discharge in order to predict any adverse siltation effects brought about by dredge discharge.
Turbidity looms as a problem in the study area primarily because the oyster shell deposits were
all associated with a matrix of plastic clay and very fine-grained quartz sand. Considering the
relatively small area a dredge can cover as opposed to the turbidity caused in this area by a high wind
and the obvious additional fact that the biologic environment has adapted to considerable turbidity
because of the natural processes at work in the area, the logical conclusion is that any damage done by
dredging will be local and temporary for most of the study area. Marsh area would have to be given very
special attention, however, since both marine biota and water fowl depend on the marsh environment, and
even temporary destruction would have some disastrous short term economic impacts.
Biological Effects
Fin fish can be affected in two ways by dredging: first by an increase in turbidity and second by
a possible disruption of their normal food supply. The local nature of dredging normally causes only a
change in fish habitat during the dredging operation. These statements are also true for benthic biota
which can move to avoid the dredge and return when favorable conditions are re-established. Bottom
dwelling organisms which are an important element in the food chain are destroyed by dredging and
normally require two or three years to re-establish themselves provided bottom conditions have not been
so altered as to make that impossible. Great care needs to be exercised in determining areas to be
dredged so as to minimize this hazard. Areas with substantial plant food for water fowl also need to be
avoided or the plant regimen needs to be re-established after dredging.
12
A lot of rhetoric has been offered regarding the potential danger of resuspending sediments that
may contain chemicals adverse to the biota. A number of cores, particularly clays, contained connate
water with hydrogen sulfide gas. If released in sufficient amounts, this gas could be chemically
adverse to the biota, but this would require a rather massive resuspension not contemplated by shell
dredging.
As was mentioned in the section dealing with interpretation of data, the oyster shell material is
contained in a matrix of plastic clay and very fine-grained quartz sand. This is typical of a deposi-tional
environment with a very low energy level. The shell units frequently overlay a coarse sand and
shell hash unit which is typical of a forebeach environment. The overburden, if any occurs, is usually
clay or fine sand. Typically, the clay material is a stiff to very plastic material which does not
easily disintegrate in water. It is our opinion that screen sizes will be important in reducing
turbidity with this clay in any dredging operation.
Based on data obtained by the Army Corps of Engineers in environmental impact statements on San
Antonio Bay in 1971, one dredge can produce approximately 1,500,000 cubic yards of shell per year with
a value of approximately $3,000,000.00. The operation would employ the services of about 90 people, 32
barges, and 8 tug boats. The average annual payroll would amount to $710,000.00. The material is valued
as a source of chemical grade lime, as poultry grits, and as oyster clutch material. It also can be used
to manufacture portland cement. The foregoing is offered in the environmental section of this report
because it is needed to compare the value of alternative resources.
RECOMMENDATIONS
The next logical step would be a closely supervised test dredging project. We recommend the Cedar
Bush Bay Area as a good place to conduct such a test. Prior to testing, base line data should be
gathered at the site so that the area can then be monitored for any adverse environmental impacts.
Particular attention should be given to the possible adverse effects of siltation and turbidity.
We further recommend that additional funds be sought to complete the coring program in this area.
The data should be reviewed not only for shell but for a sand and gravel inventory. Substantial gravel
deposits were noted during this study. Since the northeastern section of North Carolina is in very
short supply of these commodities, the feasibility of extracting these materials at the same time as the
shell needs to be evaluated.
13
APPENDICES
14
APPENDIX 1: BUDGET SUMMARY
CPRC Funds
Lease and rental of equipment, travel expenses, and purchase of expendable supplies
through June 30, 1975 $ 8,498.00
Lease and rental of equipment, travel expenses, and purchase of expendable supplies
and equipment through June 30, 1976 26,502.00
TOTAL $35,000.00
North Carolina Department of Natural and Economic Resources Funds
1. Through June 30, 1975
Division of Earth Resources $ 4,679.44
Division of Marine Fisheries 3,444.60
TOTAL $ 8,124.04
2. Through June 30, 1976
Division of Earth Resources $12,886.21
Division of Marine Fisheries 9,359.15
$30,369.40
15
APPENDIX 2: EQUIPMENT AND PERSONNEL
1. Geological and geophysical field and interpretive personnel and equipment.
a) Two geologists and one geologic technician as needed. Two technicians, part time, as needed.
(Division of Earth Resources)
b) RTT-1000 Raytheon 3.5 Khz subbottom profiler on lease from Raytheon Corporation.
c) Alpine Geophysical Company 20 foot "Vibra Core" and two technicians on lease from Alpine
Geophysical Company.
d) Crane, 900 cfm air compressor and miscellaneous equipment on lease from Waff Brothers Heavy
Equipment Company.
2. Navigation, boat location, survey personnel and equipment.
a) A registered surveyor and one technician. (Division of Marine Fisheries)
b) Range-range boat positioning equipment, the Motorola Mini-Ranger, on lease from Motorola
Corporation.
3. Boat operators, boats and barges, as needed.
a) One seventeen foot and one fifteen foot boat as needed with operator. (Enforcement Division
of Marine Fisheries)
b) One self-propelled barge with a 3 man crew as needed in the coring operation, (oyster
rehabilitation program of Marine Fisheries)
4. Computer technology and hardware to handle the navigation data.
a) One computer specialist from Marine Fisheries and two program analysts on contract from the
Computer Science Department of North Carolina State University as needed to convert range-range
data to x-y coordinate data and plot the boat tracks using the "Cal Comp" plotter.
5. Marine biology and physical oceanography, as needed. (Division of Marine Fisheries)
6. Administrative support was provided by each Division handling records and invoices for personnel
and equipment furnished for the project. Mrs. Myrtle Tyson handled budget management on behalf of
Mr. Stephen Conrad.
16
APPENDIX 3: SELECTED SEISMIC PROFILES
17
6
to
APPENDIX 4: CORE LOGS
24
SEA LEVEL AREA C PROSPECT 8
-10-Wo
dark- to light-gray, plastic clay
-20 -E=
11.0'
12.0'
very fine-grained sand with some clay
plastic clay with fine-grained sand
30
17.2' .
18.0' 1|
20.0* JS
clay with sand and oyster shell
as above
-40
Note: The core was not deep enough to evaluate total shell
thickness, so the seismic interpretation of a total
of 7 feet was used.
Shell Unit Screen Analysis
Screen Size Sample WT . Percent
.1574" 71.2 gms 13.1%
.0787 8.7 1.6
.0394 19.9 3.7
.0197 60.3 11.1
.0098 141.8 26.0
.0098> 243.1 44.5
The commercial shell was retained on the
0.1574" screen. These were oyster shells,
A 20% HC1 solution digested 67.6 gms or
94.9% and left a residue of 3.6 gms or
5.1%.
The estimated 7 foot segment analyzed
contained .92 foot of shell.
SEA LEVE L
BOTTOMf o
0.9'
10
-20-;
30-
-40
5.7'
9.4'
15.0'
CORE NUMBER 11
AREA C PROSPECT 9
dark plastic clay
very fine-grained sand with clay and oyster shells
as above
as above with clay increasing
very fine- to fine- to medium-grained sand; grading downward
coarse-grained sand-gravel
Shell Unit Screen Analysis
Screen Size Sample MT. Percent
.1574" 127.0 gms 23.6%
.0787 15.4 2.9
.0394 17.5 3.3
.0197 46.0 8.6
.0098 149.4 27.8
.0098> 182.9 33.8
The commercial shell was retained on the
0.1574" screen. These were oyster shells.
A 20% HC1 solution digested 123.8 gms or
97.5% and left a residue of 3.2 gms or
2.5%.
The 2.4 foot segment analyzed contained
0.57 foot of shell.
26
SEA LEVEL
CORE NUMBER 12
AREA C PROSPECT 7
llOTTOM
-10 -
o
1.7
2.2
].
very fine- to fine-grained sand with some clay
shell unit as above with oyster shell
-20 -
-30 -
-40
13.0
very fine- to fine-grained sand with some clay
27
SFA LEV 1
LUKL IWIBLK 14
AREA B PROSPECT 6
-10 -
IDHQII o
1.7'
3.0'
z20
-30 -
15.0'
17.6'
fine- to medium-grained sand with some clay
very fine-grained sand with clay; minor shell
dark plastic clay; scattered shells
as above with oyster shells
as above
dark plastic clay
very fine- to fine-grained sand with clay
fine- to medium- to coarse-grained sand
as above
-40
Shell Unit Screen Analysis
Screen Size Sample WT. Percent
.0787" 105.7 qms 19.6%
.0394 9.1 1.7
.0197 4.5 0.8
.0098 22.3 4.1
.0049 187.8 34.8
.0049> 211.0 39.0
The commercial shell was retained on the
0.0787" screen. These were oyster shells.
A 20% HC1 solution digested 104.2 gms or
98.6% and left a residue of 1.5 gms or 1.4%.
The 3.0 foot segment analyzed contained
0.59 foot of shell.
28
n
SEA LEVEL
CORE NUMBER 23
AREA A PROSPECT 5
-10-
liOTTOI
3.8'
very fine-grained sand with clay and few shells
as above with scattered oyster shells
20 -r
9.4' J £
as above with oyster shells
15.2'
30
-40
very fine-grained sand with clay
29
SEA LEVEL AREA A PROSPECT 5
imw 39.9 7.3
The commercial shell was retained on the
0.1574" screen. These were clam shells.
A 20% HC1 solution digested 255.8 gms or
97.1% and left a residue of 7.8 gms or 2.9%.
The 0.5 foot segment analyzed contained
.24 foot of clam shells. The analyzed
section was not the oyster shell unit and
therefore was not mapped as reserves.
32
SEA LEVEL
CORE NUMBER 39
AREA A PROSPECT 2
-10-™TTOM
very fine- to fine-grained sand with clay
4.6'
6'
6.6'
8.3 1
very fine- to fine-grained sand
dark plastic clay with some sand and oyster shells
as above
very fine-grained sand with some clay
-20-
medium- to coarse-grained sand with shell hash
13.6'
30 -
-40
Shell Unit Screen Analysis
Screen Size Sample WT . Percent
.1574" 98.8 gms 18.3%
.0787 15.8 2.9
.0394 13.7 2.5
.0197 8.2 1.5
.0098 112.2 28.8
.0098> 290.0 46.0
The commercial shell was retained on the
0.1574" screen. These were oyster shells.
A 20% HC1 solution digested 96.6 gms or
97.8% and left a residue of 2.2 gms or 2.2%.
The 2.0 foot segment analyzed contained
0.37 foot of shell.
33
SEA LEVEL
-10 -i
1 10TT0. 1
o
2.3 1
4.6'
f 6.7'
20—
30 -
40
9.5'
12.8'
15.3
15.8'
CORE NUMBER 40
AREA A PROSPECT 2
dark plastic clay
very fine- to fine-grained sand
dark plastic clay
dark plastic clay with oyster shells
very fine- to fine-grained sand with clay
coarse-grained, yellow-brown gravel
coarse-grained, dark-brown gravel with shell hash
34
SEA LEVEL
10 -
iionnii
^^-±-i 1.6'
-20 -
4.7'
7.2'
30
-40
14.1
LUKt NUPlBtK 41
AREA A PROSPECT 1
fine- to medium-grained sand
dark plastic clay
very fine- to fine-grained sand
coarse shell hash with coarse-grained sand
35
q SEA LEVE L
-in
-20
ISfflQ
-30-
-40
6.6 1 ,1
7.T 3!
IT
13.1
CORE NUMBER 42
AREA A PROSPECT 1
very fine-grained sand
as above with shell fragments
very fine-grained sand with clay and oyster shells
fine-grained, light-gray sand
coarse-grained sand with wood fragments
36
SEA LEVEL
-10
BOTTOM n
-20
-30-
-40
0.5' -
1.1'I 3:
11.4'
16.9'
COPE NUMBER 43
AREA A PROSPECT 1
very fine-grained sand with clay
as above with shell
very fine-grained sand with few shells and some clay
coarse shell hash with coarse-grained sand
37
SEA LEVEL
10-
-20 -fc
IlOTTO
-30
o
1.0'
2.0'
T^TTTT^ 18.0' mm i8.9'
-40
CORE NUMBER M
AREA A PROSPECT 1
very fine-grained sand with some clay
as above with shell
very fine-grained sand with some clay; shell increasing with depth
medium-grained, gray-yellow sand
38
SEA LEVEL
-10
CORE NUMBER 51
AREA A PROSPECT 5
lIpTTOHn
-20
-30
-40
9'
12.6'
13.6'
15'
16'
very fine-grained sand with clay
dark plastic clay
very fine-grained sand with clay
very fine- to fine-grained sand
very fine- to fine-grained sand with shell hash
as above
as above
Shell Unit Screen Analysis
Screen Size Sample WT. Percent
.0787" 102.9 gm 19.5%
.0394 72.4 13.7
.0197 216.7 41.1
.0098 107.4 20.4,
.0049 21.3 4.0
.0049> 6.8 1.3
The commercial shell was retained on the
0.0787" screen. These were clam shells.
A 20% HC1 solution digested 60.1 gms or
79.1% and left a residue of 42.8 qms or
21%.
The 3.4 foot segment analyzed contained
.66 foot of shell. The analyzed section
was not the oyster shell unit and there-fore
was not mapped as reserves.
39
SEA LEVEL
-10
20
-30-
3.0'
3.7'
6.0'
8.2'
-40
14.4'
KJKt NUHBtK bZ
AREA A PROSPECT 5
very fine- to fine-grained, tan-gray sand with some shell
very fine- to fine-grained sand with clay
very fine- to coarse-grained sand with dark plastic clay and
oyster shells
fine-grained sand
fine- to medium- to coarse-grained sand with gravel
Shell Unit Screen Analysis
Screen Size Sample WT. Percent
.1574" 160.7 gms 29.8%
.0787 24.2 4.5
.0394 32.5 6.0
.0197 57.4 10.6
.0098 87.4 16.2
. 0098 > 177.4 32.9
The commercial shell was retained on the
0.1574" screen. These were oyster shells
A 20% HC1 solution digested 151.1 gms or
94% and left a residue of 9.6 gms or 6%.
The 2.3 foot segment analyzed contained
0.68 foot of shell.
40
SEA LEVEL
CORE NUMBER 55
AREA A PROSPECT 2
-10 -
norm
r^r-
3.0'
4.0'
6.0'
7.4'
10.0'
11.0'
very fine-grained sand and plastic clay with minor clam shells
dark plastic clay
dark plastic clay, fine-grained sand with oyster shells
as above
dark plastic clay, fine-grained sand
medium- to coarse-grained sand with gravel
-30-
40
16.1
fine- to medium-grained sand, interbedded yellow-tan-gray-black layers
Shell Unit Screen Analysis
Screen Size Sample WT . Percent
.1574"
.0787
.0394
.0197
.0098
.0098>
154.7 gms
13.8
13.8
15.2
22.2
199.0
37.0%
3.3
3.3
3.6
5.3
47.5
The commercial shell was retained on the
0.1574" screen. These were oyster shells.
A 20% HC1 solution digested 153.2 gms or 99%
and left a residue of 1.5 gms or 1%.
The 3.4 foot segment analyzed con-tained
1.26 feet of shell.
41
SEA LEVEL
CORE NUMBER 57
AREA A PROSPECT 2
-10-
IIOTTOM
-20
-
:
2.T ^
3.0'
6.0'
8.2'
9.0'
.mmm 12.0'
•30-
-40
dark plastic clay
as above with some sand and oyster shells
as above
as above
fine- to medium-grained sand with clay; some shells
fine- to medium-grained sand
Shell Unit Screen Analysis
Screen Size Sample WT . Percent
.1574" 187.8 gm 36.7%
.0787 14.2 2.8
.0394 12.1 2.4
.0197 20.5 3.9
.0098 2.6 0.5
.0098> 275.0 53.7
The commercial shell was retained on
the 0.1574" screen. These were oyster
shells. A 20% HC1 solution digested
186.8 gms or 99.5% and left a residue
of 1.0 gms or 0.5%.
The 6.1 foot segment analyzed contained
2.24 feet of shell.
42
SEA LEVEL
CORE NUMBER 58
AREA A PROSPECT 3
IlOTTOII
-10-
o
1.2'
3.6'
very fine-grained sand
very fine-grained sand with oyster shells
10.0'
-20
-30-
-40
fine-grained sand with clay, some shell
43
SEA LEVEL
-10
-20
4.8'
7.T
8.1'
12.
9
1
CORE NUMBER 59
AREA A PROSPECT 3
fine- to medium-grained sand
dark plastic clay with sand
plastic clay with oyster shells
fine- to medium-grained sand with shell hash
-30
40
44
SEA LEVEL
toiwo
10
-20-
W2.
30
W
1.8'
3.0 1
4.6'
6.0'
7.7'
10.7'
13.4'
14'
CORE NUMBER 60
AREA A PROSPECT 3
very fine- to fine-grained sand
as above with scattered shells
fine-grained sand with clay and shells
dark plastic clay; sand with oyster shells
clay as above grading to sand; no shells
medium-grained sand with minor shell
coarse-grained sand; some shell hash
coarse-grained, tan sand with shell hash
Shell Unit Screen Analysis
Screen Size Sample WT . Percent
.0787" 76.6 gms 15.6%
.0394 6.20 1.3
.0197 11.80 7.4
.0098 98.28 20.0
.0049 140.00 28.4
.0049> 149.42 32.3
The commercial shell was retained on the
0.0787" screen. These were oyster shells.
A 20% HC1 solution digested 73.3 gms or
96.1% and left a residue of 3.0 gms or 3.9%.
The 1.4 foot segment analyzed contained 0.22
foot of shell
.
45
APPENDIX 5: CORE HOLE LOCATIONS: RANGE-RANGE DATA
Core
No.
Line
Designation
West Bridge
Meters Feet
East Bridge
Meters Feet
1 Shipyard Channel Bridge
2 S-14-10 4482 14705 5746 18853
3 S-14-5 4617 15148 5260 17258
4 TV-A 6253 20516 7065 23180
5 TV -30 6394 20979 6062 19889
6 T-19 7844 25736 5875 19276
7 U-21-6 9659 31691 8130 26675
8 U-23-1 10776 35356 9581 31435
9 U-24 12010 39405 11010 36124
10 V-25-4 12535 41127 12037 39493
11 V-26 13228 43401 12909 42354
12 V-27-12 9907 32505 9907 32505
13 V-28-7 8477 27813 8430 27659
14 VS-T-31 4897 16067 4680 15355
15 VR-T-32 3885 12747 3672 12048
16 VQ-T-33 3132 10276 2710 8892
17 VP-T-34 2610 8563 2546 8353
18 V-35 2196 7205 2311 7582
19 P-5 4450 14600 1096 3596
20 Q-6 5180 16996 1956 6418
21 R-ll 5701 18705 3100 10171
22 S-13 6655 21835 4210 13813
23 P-2 1183 3881 4605 15109
24 Q-8 2220 7284 4647 15247
25 R-9 3400 11155 5106 16753
26 S-15 4572 15001 6086 19968
2 7 T-16 5893 19335 7223 23699
23 N-28-11 12701 41672 215 705
29 4WN-T 13338 43762 847 2779
30 4WM-T 13091 42952 1157 3796
31 4W-2-4 12857 42184 1800 5906
32 4WL-T-3 12857 42184 2585 8481
33 4WK-T-22 12729 41764 3148 10329
34 4WJ-T-19 12552 41183 4424 14515
35 4W-5 12580 41275 5225 17143
36 4WI-T 12655 41521 6100 20014
37 4WH-T 12884 42272 6917 22695
38 4WG-T 13316 43690 7905 25936
39 4WF-T 14030 46032 8662 28420
40 4WE-T 14837 48680 9661 31698
41 4WD-T 15466 50744 10659 34972
42 4WC-T 16221 53221 11725 38470
43 4WB-T 16920 55515 12632 41446
44 4WA-T 17285 56712 13108 43007
45 AB-T-(B-2) 17397 57080 12599 41337
46 C-5± 16312 53520 11352 37246
4 7 D-6± 15647 51338 10437 34244
4? E-9± 15142 49681 9353 30687
49 F-10+ 14501 47578 8682 28486
50 G-12-10± 14065 46147 7762 25467
51 M-26 11204 36760 1725 5660
52 L-25 11397 37394 2315 7596
53 K-21 11202 37654 3636 11930
54 J-20 11661 38260 4378 14364
55 H-15 12465 40898 7083 23239
56 G-12 12950 42489 8163 26783
57 F-ll 13508 44320 8863 29080
58 2W/1S-12+ 9607 31521 6230 20441
59 2W/2S-T-12-6 9875 32400 5002 16412
60 4S ext. 9580 31432 3510 11516
46
APPENDIX 6: FUTURE CORE POINTS
Line Designation Locat ion*
PM3 MM7
PM1 MM7
PM2
PM3 MM5
MM9
PM4 MM3
PM1 MM2
PM3 MM8
PM4 MM4
PM5 MM4
PM6 MM3
PM5 MM4
PM3 MM!
PM1 MM2
PM2 MM7
PM12
PM8 MM2
PM6 MM5
PM6 MM!
PM1 MM2
PM4 MM4
PM4 MM9
PM7
PM9 MM5
PM8
PM9
PM10 MM6
PM14 MM3
PM26 MM3
PM17 MM2
PM10 MM2
PM15
PM7 MM4
PM6 MM4
PM4 MM3
PM1 MM5
PM11 MM5
PM11
PM8
PM6 MM4
PM2 MM! 2
PM2 MM16
PM2 MM28
PM2 MM31
PM1 MM10
PM1 MM125
PM1 MM5
PM2 MM6
ne Designation Location*
IS PM1 MM17
PM1 MM8
PM1
PM1 MM3
C PM4 MM1
DE PM7 MM4
E PM8 MM!
FG PM11 MM 3
G PM12 MM2
PM12 MM6
H PM14 MM6
PM14 MM 10
HI PM15 MM5
I PM16 MM7
PM16 MM10
L PM24 MM 16
PM25 MM 3
PM26 MM3
PM26 MM8
PM26 MM10
P PM4 MM5
o. PM7 MM2
PM13 MM6
PM13 MM9
PM13 MM15
T PM16 MM6
PM17 MM3
PM17 MM5
U PM23 MM6
PM20 MM6
V PM25 MM4
PM25 MM 10
PM26 MM5
PM27 MM13
2W PM12
PM15
MM3
3W PM1 MM 7
IN shadow PM3
2N shadow PM4
PM3
MM3
4N shadow PM2 MM8
PM1 MM5
5N shadow PM1 MM11
3S ext PM7 MM3
PM1 MM5
5S ext PM3 MM6
16N
15N
14N
13N
13
12N
ION
9N
8N
7N rerun
6N
5N
4N west
3N
2N
IN
* PM refers to Position Mark and MM to Minute Mark and are so indicated on the seismic lines and ranqe-range
data.
47
SMC DEMS LIBRARY
1610 IV5SC
RALEjOK.NC 27699-1 6 1
919-715-4161